Toxic Effects Of Typical Industry Wastewater And Environmental Contaminants On Alga

The toxicity effect of four industrial wastewaters (pharmaceutical wastewater, petrochemical wastewater, dying wastewater and coking wastewater) and environmental contaminants (Cd2+ and SDBS) were investigated using Scenedesmus obliquus, moreover, influence of dissolved organic matter on toxic effects of environmental contaminants was also studied.Firstly, chlorophyll-a synthesis as the test index to evaluate the performance for toxicity removal of petrochemical and pharmaceutical wastewater treatment techniques, compare the toxicity of effluents of four industry wastewater, analyze the relationship between wastewater toxicity and physical and chemical parameters. The results showed that, toxicity of both petrochemical and pharmaceutical wastewater were removed by their own treatment techniques, TUa from 20 to 7 and 2700 to 2 for petrochemical wastewater and pharmaceutical wastewater, respectively. Effluents toxicity order of four industry wastewater was petrochemical wastewater>dying wastewater>coking wastewater>pharmaceutical wastewater. The concentration of COD and NH3-N were significant positive correlated with wastewater toxicity (P<0.01).Secondly, sensitivity of the four toxicity evaluation index (chlorophyll-a synthesis, cell density, superoxide dismutase and cell membrane integrity) on single toxicity of Cd2+ and SDBS were compared. The joint toxicity of Cd2+ and SDBS were evaluated by using the additive index (AI) and isobologram. The results showed that, the most sensitive test index in the four endpoints was Chlorophyll-a. The EC50 in Chl-a synthesis for Cd2+ and SDBS were 0.020 and 70 mg/L, respectively. It can be seen that Cd2+ was more hazardous than SDBS. The results of AI and isobologram to evaluate the joint actions were same, which indicated that the joint actions of these two chemicals were synergism to S. obliquus.Finally, the influence of dissolved organic matter on the toxic effects of Cd2+ and SDBS were investigated using Chl-a synthesis. The results showed that, fulvic acid (FA) had no significant effect on the single toxicity of Cd2+. The concentration of FA was positively correlated with the single toxicity of SDBS. The toxicity of Cd2+ and SDBS in mixed system would increase after adding FA with different mixture ratio, moreover, higher concentration (25 mg/L) of FA would made these increase more significantly.This study may provide the basic data to evaluate the aqua-ecosystem risk on alga which caused by industry wastewater discharge and provide a reference for pollutants discharge standards.